The invention discloses a data-free federated
distillation method and
system based on zero-order
gradient estimation, and the method comprises the steps: initializing a
global model and a synthetic image generator through a central
server, generating a synthetic image sample in each communication round, transmitting the synthetic image sample to a
client, and enabling the
client to update a local model through local privacy data, and uploading a prediction result. And the central
server calculates the gradient of the generator by using a zero-order
gradient estimation technology, and updates generator parameters and
global model parameters. And by introducing fidelity loss, adversarial loss, diversity loss and negative information entropy loss, the performance of the generator is optimized. And the gradient of the generator is calculated through zero-order
gradient estimation, so that the requirement of accessing a local model of a
client is avoided, and privacy is effectively protected. The
global model is updated by minimizing knowledge
distillation loss, and at the same time, the client further optimizes the local model by receiving an integrated prediction result. The method has the
advantage that the
communication bandwidth requirement is reduced by reducing the access to the private data of the client.